1. Humidity regime of the room which is directly related to the heating regime is of a great importance. Optimal relative humidity of an inhabited room is 50-60%. The sources of humidity in a room are preparation of food, washing and ironing, taking a shower, taking a bath, tidying up, plants, human sweat secretion. An average family may bring in up to 15 l of humidity in 24 hours to the atmosphere of their lodging. Humidity appears in the air in the form of vapor, and the maximum amount of humidity depends on the air temperature:

For example, if there is 10,7g/m3 humidity in the room at 20oC temperature, the temperature will drop to 12oC, the humidity of the air will rise to 100%, and the following lowering of the temperature will result in humidity condensation and its eventual falling mainly on building constructions that grow cold very fast. Therefore, if during the cold period of the year you go to your country-house, or, vice versa, you live there constantly, but sometimes you leave for a long period of time, it necessary to thoroughly ventilate the room before leaving. This will protect the fencing constructions of the building against humidity condensation, putrefaction, soaking and the formation of mould. Increased humidity of fencing constructions results in the increased loss of heat.   
  
2. For instance, there is a long-term database of the European part of the Russian Federation about maximum out of the average (by rhumbs) speeds of the wind and the maximum (out of the average) temperature traits of the coldest month - January. The average temperature of the European part of the Russian Federation is -3,6oC, the direction of the wind (the average, by rhumbs) is south-west. 
An example of the influence of the wind on the amount of total loss of heat for a 2,5- brick building: 
 

Additional Heat
1. Heat may appear in the room owing to working electrical heating appliances, radio and TV equipment, a refrigerator, a washing machine, an iron, a hair-drier or another electrical appliance. A considerable amount of heat is emitted during preparation of food. Look around your house: if you know, for example, the amount of electric bulbs that are turned on and their total power as well as that of any other working electric appliance, you can count an approximate amount of additional heat coming to your house. As regards the example presented in the previous section of the website, for a 100 m2 room this would be 2-3 kW an hour.
2. Heat energy is also emitted by humans and domestic animals. For example, performing a light, medium and hard work, a human being emits on average up to 172 W; 172-193 W; and more than 193 W respectively. You can count yourself.
3. There is a positive factor, a plus part of a heat balance, in the nature. It is insolation (solar radiation). 
 

The temperature rates in the table are derived on the basis of statistic data of the intensity of the influence of solar radiation on the surface of walls and windows (W/m2) and its duration (an hour), geographical width 60o.
4. Rarely do we consider for a moment what is comfort when we fell well and cozy. On the other hand, a state of heat discomfort when our feet are cold, when there is a draught and the walls grow damp may cause disbalance and disturbs a fully fledged living, working or resting. There are certain physical parameters of all comfortable conditions in the lodging. Consequently, they may be controlled and regulated.    
Heat Parameters of the Room
 

According to recommendations of normative literature, an 18oC temperature is accepted to determine the loss of heat and selection of heat generator in the winter period.
A normative temperature drop between the air temperature inside living quarters, external wall, camp ceiling and the fist floor is no bigger than 6,4 and 2oC respectively. Remember this and do not hang your thermometer on the external wall of the room. It will obviously cheat you. Hygienists recommend to lower the temperature in the bedroom by 2-3oC at night; this is related to the change of intensity of metabolism.
Conclusion
Now you are familiar with the essentials of the heat balance of a building. This knowledge will help you to individually choose the equipment necessary for heating a certain room or to assign this task for professionals.